[PATCH next] nvdimm: Prevent integer overflow in ramdax_get_config_data()

[Dan Carpenter]

The "cmd->in_offset" variable comes from the user via the __nd_ioctl()
function.  The problem is that the "cmd->in_offset + cmd->in_length"
addition could have an integer wrapping issue if cmd->in_offset is close
to UINT_MAX .  The "cmd->in_length" variable has been capped, but the
"cmd->in_offset" variable has not.  Both of these variables are type u32.

Fixes: 43bc0aa19a21 ("nvdimm: allow exposing RAM carveouts as NVDIMM DIMM 
devices")
Signed-off-by: Dan Carpenter <dan.carpen...@linaro.org>
---
 drivers/nvdimm/ramdax.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvdimm/ramdax.c b/drivers/nvdimm/ramdax.c
index 63cf05791829..faa6f3101972 100644
--- a/drivers/nvdimm/ramdax.c
+++ b/drivers/nvdimm/ramdax.c
@@ -143,7 +143,7 @@ static int ramdax_get_config_data(struct nvdimm *nvdimm, 
int buf_len,
                return -EINVAL;
        if (struct_size(cmd, out_buf, cmd->in_length) > buf_len)
                return -EINVAL;
-       if (cmd->in_offset + cmd->in_length > LABEL_AREA_SIZE)
+       if (size_add(cmd->in_offset, cmd->in_length) > LABEL_AREA_SIZE)
                return -EINVAL;
 
        memcpy(cmd->out_buf, dimm->label_area + cmd->in_offset, cmd->in_length);
-- 
2.51.0